Turn the Instant Pot to the sauté setting. Add 1 teaspoon of oil and heat briefly.
Add the minced garlic and sauté for about 30 seconds or until fragrant, careful not to burn.
Add the broken fettuccine noodles directly into the pot.
Pour in 2 ½ cups of low-sodium chicken or vegetable broth, ensuring noodles are submerged.
Sprinkle in salt, pepper, onion powder, dried basil, and dried parsley flakes. Stir gently to combine.
Secure the lid, set steam release valve to sealing, cook on high pressure for 5 minutes.
Allow pressure to release naturally for 5 minutes, then quick release remaining pressure.
Remove lid and stir cooked fettuccine.
Whisk together milk and cornstarch in a small bowl until smooth. Pour into the pot and stir to thicken sauce.
Stir in freshly grated parmesan cheese until melted and creamy. Adjust seasoning with salt and pepper as needed.
Spoon into bowls, garnish with extra parsley or cheese if desired, and serve hot.